U.S. patent number 5,927,257 [Application Number 08/934,298] was granted by the patent office on 1999-07-27 for pressure compensating exhaust gas recirculation valve.
This patent grant is currently assigned to Caterpillar Inc. Invention is credited to David E. Hackett.
United States Patent |
5,927,257 |
Hackett |
July 27, 1999 |
Pressure compensating exhaust gas recirculation valve
Abstract
A valve assembly for use in an internal combustion engine is
disclosed. The valve assembly includes a housing which defines a
chamber. The housing further defines an outlet, a first inlet, and
a second inlet, each of which is in fluid communication with the
chamber. The valve assembly further includes a master valve
positioned within the chamber. The master valve isolates the first
inlet from the outlet when the master valve is positioned in a
seated master position. The master valve places the first inlet in
fluid communication with the outlet when the master valve is
located in an open master position. The valve assembly still
further includes a slave valve positioned within the chamber. The
slave valve isolates the second inlet from the outlet when the
slave valve is positioned in a seated slave position. The slave
valve places the second inlet in fluid communication with the
outlet when the slave valve is located in an open slave position.
Movement of the master valve from the seated master position to the
open master position causes movement of the slave valve from the
seated slave position to the open slave position. The master valve
moves a distance from the seated master position toward the open
master position while the slave valve is positioned in the seated
slave position. A method of controlling a flow of engine exhaust is
also disclosed.
Inventors: |
Hackett; David E. (Washington,
IL) |
Assignee: |
Caterpillar Inc (Peoria,
IL)
|
Family
ID: |
25465322 |
Appl.
No.: |
08/934,298 |
Filed: |
September 19, 1997 |
Current U.S.
Class: |
123/568.26;
137/607; 251/282; 251/129.07 |
Current CPC
Class: |
F02M
26/53 (20160201); F02M 26/69 (20160201); F16K
11/161 (20130101); F02M 26/38 (20160201); Y10T
137/87692 (20150401); F02M 26/16 (20160201); F02M
26/42 (20160201) |
Current International
Class: |
F02M
25/07 (20060101); F16K 11/16 (20060101); F16K
11/10 (20060101); F02B 047/08 (); F16K
031/30 () |
Field of
Search: |
;123/568.16,568.25,568.26 ;251/129.15,30.01,129.2,149,282,129.07
;137/607,630.22 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
0770775A1 |
|
May 1997 |
|
EP |
|
2103766 |
|
Feb 1983 |
|
GB |
|
Primary Examiner: Dolinar; Andrew M.
Assistant Examiner: Castro; Arnold
Attorney, Agent or Firm: Maginot, Addison & Moore
Claims
What is claimed is:
1. A valve assembly, comprising:
a housing defining a chamber, said housing further defining (1) an
outlet, (2) a first inlet, and (3) a second inlet, each being in
fluid communication with said chamber;
a master valve positioned within said chamber, said master valve
(1) isolates said first inlet from said outlet when said master
valve is positioned in a seated master position, and (2) places
said first inlet in fluid communication with said outlet when said
master valve is located in an open master position; and
a slave valve positioned within said chamber, said slave valve (1)
isolates said second inlet from said outlet when said slave valve
is positioned in a seated slave position, and (2) places said
second inlet in fluid communication with said outlet when said
slave valve is located in an open slave position;
wherein movement of said master valve from said seated master
position to said open master position causes movement of said slave
valve from said seated slave position to said open slave position;
and
wherein said master valve moves a distance from said seated master
position toward said open master position while said slave valve is
positioned in said seated slave position.
2. The assembly of claim 1, wherein:
said master valve has a pressure compensation channel defined
therein, and
said pressure compensation channel enables fluid communication
between said chamber and said outlet when said master valve is
located in said seated master position.
3. The assembly of claim 1, wherein:
said slave valve has a passageway defined therethrough, and
said master valve is positioned within said passageway.
4. The assembly of claim 3, wherein said housing further defines a
plunger opening, further comprising:
a plunger which extends into said chamber through said plunger
opening;
a first spring positioned within said chamber and interposed
between said housing and said plunger, said first spring biases
said plunger into contact with said master valve; and
a second spring positioned within said chamber and interposed
between said plunger and said slave valve.
5. The assembly of claim 4, wherein:
said first spring biases said master valve toward said seated
master position, and
said second spring biases said slave valve toward said seated slave
position.
6. The assembly of claim 1, further comprising a first spring and a
second spring, wherein:
said first spring biases said master valve toward said seated
master position,
said second spring biases said slave valve toward said seated slave
position,
pressure at said first inlet biases said master valve toward said
open master position, and
pressure at said second inlet biases said slave valve toward said
open slave position.
7. The assembly of claim 3, wherein:
said master valve includes a shoulder located on an exterior
surface thereof, and
movement of said master valve from said seated master position to
said open master position causes said shoulder to contact said
slave valve thereby moving said slave valve from said seated slave
position to said open slave position.
8. The assembly of claim 7, wherein:
said shoulder is spaced apart from said slave valve when (1) said
slave valve is located in said seated slave position, and (2) said
master valve is located in said seated master position.
9. An engine assembly, comprising:
an internal combustion engine having an engine air inlet, a first
engine exhaust outlet, and a second engine exhaust outlet;
a valve housing defining a chamber, said housing further defining
(1) a valve housing outlet, (2) a first valve housing inlet, and
(3) a second valve housing inlet, each being in fluid communication
with said chamber;
a master valve positioned within said chamber, said master valve
(1) isolates said first valve housing inlet from said valve housing
outlet when said master valve is positioned in a seated master
position, and (2) places said first valve housing inlet in fluid
communication with said valve housing outlet when said master valve
is located in an open master position; and
a slave valve positioned within said chamber, said slave valve (1)
isolates said second valve housing inlet from said valve housing
outlet when said slave valve is positioned in a seated slave
position, and (2) places said second valve housing inlet in fluid
communication with said valve housing outlet when said slave valve
is located in an open slave position,
wherein said first engine exhaust outlet is in fluid communication
with said first valve housing inlet,
wherein said second engine exhaust outlet is in fluid communication
with said second valve housing inlet,
wherein said engine air inlet is in fluid communication with said
valve housing outlet,
wherein movement of said master valve from said seated master
position to said open master position causes movement of said slave
valve from said seated slave position to said open slave position,
and
wherein said master valve moves a distance from said seated master
position toward said open master position while said slave valve is
positioned in said seated slave position.
10. The assembly of claim 9, wherein:
said master valve has a pressure compensation channel defined
therein, and
said pressure compensation channel enables fluid communication
between said chamber and said valve housing outlet when said master
valve is located in said seated master position.
11. The assembly of claim 9, wherein:
said slave valve has a passageway defined therethrough, and
said master valve is positioned within said passageway.
12. The assembly of claim 11, wherein said housing further defines
a plunger opening, further comprising:
a plunger which extends into said chamber through said plunger
opening;
a first spring positioned within said chamber and interposed
between said housing and said plunger, said first spring biases
said plunger into contact with said master valve; and
a second spring positioned within said chamber and interposed
between said plunger and said slave valve.
13. The assembly of claim 12, wherein:
said first spring biases said master valve toward said seated
master position, and
said second spring biases said slave valve toward said seated slave
position.
14. The assembly of claim 12, further comprising a first spring and
a second spring, wherein:
said first spring biases said master valve toward said seated
master position,
said second spring biases said slave valve toward said seated slave
position,
pressure at said first valve housing inlet biases said master valve
toward said open master position, and
pressure at said second valve housing inlet biases said slave valve
toward said open slave position.
15. The assembly of claim 11, wherein:
said master valve includes a shoulder located on an exterior
surface thereof, and
movement of said master valve from said seated master position to
said open master position causes said shoulder to contact said
slave valve thereby moving said slave valve from said seated slave
position to said open slave position.
16. The assembly of claim 15, wherein:
said shoulder is spaced apart from said slave valve when (1) said
slave valve is located in said seated slave position, and (2) said
master valve is located in said seated master position.
17. A method of controlling a flow of engine exhaust, comprising
the steps of:
providing a valve assembly which includes (a) a housing defining a
chamber, the housing further defining (1) a valve housing outlet,
(2) a first valve housing inlet, and (3) a second valve housing
inlet, each being in fluid communication with the chamber, (b) a
master valve positioned within the chamber, the master valve (1)
isolates the first valve housing inlet from the valve housing
outlet when the master valve is positioned in a seated master
position, and (2) places the first valve housing inlet in fluid
communication with the valve housing outlet when the master valve
is located in an open master position, and (c) a slave valve
positioned within the chamber, the slave valve (1) isolates the
second valve housing inlet from the valve housing outlet when the
slave valve is positioned in a seated slave position, and (2)
places the second valve housing inlet in fluid communication with
the valve housing outlet when the slave valve is located in an open
slave position;
providing an internal combustion engine having an engine air inlet,
a first engine exhaust outlet, and a second engine exhaust outlet,
wherein (1) the first engine exhaust outlet is in fluid
communication with the first valve housing inlet, (2) the second
engine exhaust outlet is in fluid communication with the second
valve housing inlet, and (3) the engine air inlet is in fluid
communication with the valve housing outlet;
moving the master valve a first distance from the seated master
position to an intermediate master position while the slave valve
is positioned in the seated slave position; and
moving the master valve a second distance from the intermediate
master position to the open master position so as to cause movement
of the slave valve from the seated slave position to the open slave
position whereby engine exhaust is enabled to flow from the first
and second engine exhaust outlet to the engine air inlet.
18. The method of claim 17, wherein:
the master valve has a pressure compensation channel defined
therein, and
the pressure compensation channel enables fluid communication
between the chamber and the valve housing outlet when the master
valve is located in the seated master position.
19. The method of claim 17, wherein:
the slave valve has a passageway defined therethrough, and
the master valve is positioned within the passageway.
20. The method of claim 17, wherein:
the master valve includes a shoulder located on an exterior surface
thereof,
the step of moving the master valve the first distance includes the
step of moving the shoulder so as to contact the slave valve,
and
the step of moving the master valve the second distance includes
the step of moving the shoulder so as to cause the slave valve to
be moved from the seated slave position to the open slave position.
Description
TECHNICAL FIELD OF THE INVENTION
The present invention relates generally to an exhaust gas
recirculation (EGR) valve for an internal combustion engine, and
more specifically to a pressure compensating EGR valve for an
internal combustion engine.
BACKGROUND OF THE INVENTION
During operation of an internal combustion engine, it is desirable
to control the formation and emission of certain gases, such as the
oxides of nitrogen (NO.sub.x). One method of achieving this result
is the use of EGR which is a process whereby exhaust gases are
selectively routed from the exhaust manifold or manifolds to the
intake manifold of the internal combustion engine. The use of EGR
reduces the amount of NO.sub.x produced during operation of the
internal combustion engine. In particular, NO.sub.x is produced
when nitrogen and oxygen are combined at high temperatures
associated with combustion. The presence of chemically inert gases,
such as those gases found in the exhaust of the engine, inhibits
nitrogen atoms from bonding with oxygen atoms thereby reducing
NO.sub.x production.
However, EGR is only needed during certain engine operating
conditions. Hence, a valve, commonly referred to as an EGR valve,
is used to selectively route a portion of the exhaust gases from
the exhaust manifold or manifolds to the intake manifold. With the
use of microprocessors, an engine control module can rapidly
process a number of sensor inputs to determine when the use of EGR
would be most advantageous. Moreover, operating conditions often
change quickly during normal operation of the engine thereby
requiring the EGR valve to open and close rapidly.
The EGR valve must also be "fail safe". More specifically, the EGR
valve should remain in a closed position if any of the components
associated therewith (e.g. the engine control module) fail or
otherwise become inoperable. Such fail safe operation generally
requires use of a spring that biases the valve into the closed
position. The magnitude of the spring bias must be large enough to
hold the valve closed during extreme engine operating conditions
such as when the exhaust gases within the engine exhaust manifold
is at or near its maximum pressure. An actuator, such as a
solenoid, selectively provides a force to overcome the spring bias
in order to open the EGR valve. It should be appreciated that the
time period necessary for the solenoid to overcome the spring bias
of the spring is proportional to the magnitude of the spring bias.
In particular, the time period necessary for the solenoid to
overcome the spring bias of the spring increases as the magnitude
of the spring bias increases. Hence, a tension exists between the
desirability of rapid opening and closing of the EGR valve and the
desirability of fail safe operation. Such tension is a drawback
associated with EGR valves which have heretofore been designed.
Also, many engines used in heavy machinery, such as earth moving
equipment, are turbocharged diesel engines. In a turbocharged
diesel engine, it is often advantageous to divide the exhaust
manifold into two smaller manifolds. Each of the two smaller
manifolds routes a portion of the exhaust gases therein to a
separate inlet on opposite sides of the turbocharger turbine disk.
Applying exhaust gases to the turbine disk in such a manner
accelerates the turbine disk more rapidly relative to applying all
of the exhaust gases to only one side of the turbine disk. Such
rapid turbine acceleration allows the engine to respond more
quickly to increased load conditions. A drawback to the use of EGR
with two separate exhaust manifolds is that exhaust gases are
desirably extracted from each exhaust manifold equally. In
particular, an equal amount of exhaust gases are desirably
extracted from each of the exhaust manifolds in order to place an
equal load on each half of the engine. Thus, it is desirable for
the EGR valve or valves to extract exhaust gases equally from each
of the exhaust manifolds.
What is needed therefore is an apparatus and method for selectively
routing EGR gases which overcome one or more of the above-mentioned
drawbacks.
SUMMARY OF THE INVENTION
In accordance with a first embodiment of the present invention,
there is provided a valve assembly. The valve assembly includes a
housing which defines a chamber. The housing further defines an
outlet, a first inlet, and a second inlet, each of which is in
fluid communication with the chamber. The valve assembly further
includes a master valve positioned within the chamber. The master
valve isolates the first inlet from the outlet when the master
valve is positioned in a seated master position. The master valve
places the first inlet in fluid communication with the outlet when
the master valve is located in an open master position. The valve
assembly still further includes a slave valve positioned within the
chamber. The slave valve isolates the second inlet from the outlet
when the slave valve is positioned in a seated slave position. The
slave valve places the second inlet in fluid communication with the
outlet when the slave valve is located in an open slave position.
Movement of the master valve from the seated master position to the
open master position causes movement of the slave valve from the
seated slave position to the open slave position. The master valve
moves a distance from the seated master position toward the open
master position while the slave valve is positioned in the seated
slave position.
In accordance with a second embodiment of the present invention,
there is provided an engine assembly. The engine assembly includes
an internal combustion engine having an engine air inlet, a first
engine exhaust outlet, and a second engine exhaust outlet. The
engine assembly further includes a valve housing which defines a
chamber. The housing further defines a valve housing outlet, a
first valve housing inlet, and a second valve housing inlet, each
of which is in fluid communication with the chamber. The engine
assembly also includes a master valve positioned within the
chamber. The master valve isolates the first valve housing inlet
from the valve housing outlet when the master valve is positioned
in a seated master position. The master valve places the first
valve housing inlet in fluid communication with the valve housing
outlet when the master valve is located in an open master position.
The engine assembly still further includes a slave valve positioned
within the chamber. The slave valve isolates the second valve
housing from the valve housing outlet when the slave valve is
positioned in a seated slave position. The slave valve places the
second valve housing in fluid communication with the valve housing
outlet when the slave valve is located in an open slave position.
The first engine exhaust outlet is in fluid communication with the
first valve housing inlet. The second engine exhaust outlet is in
fluid communication with the second valve housing inlet. The engine
air inlet is in fluid communication with the valve housing outlet.
Movement of the master valve from the seated master position to the
open master position causes movement of the slave valve from the
seated slave position to the open slave position. The master valve
moves a distance from the seated master position toward the open
master position while the slave valve is positioned in the seated
slave position.
In accordance with a third embodiment of the present invention,
there is provided a method of controlling a flow of engine exhaust.
The method includes the step of providing a valve assembly which
includes a housing that defines a chamber. The housing further
defines a valve housing outlet, a first valve housing inlet, and a
second valve housing inlet, each of which is in fluid communication
with the chamber. The valve assembly includes a master valve
positioned within the chamber. The master valve isolates the first
valve housing inlet from the valve housing outlet when the master
valve is positioned in a seated master position. The master valve
places the first valve housing inlet in fluid communication with
the valve housing outlet when the master valve is located in an
open master position. The valve assembly includes a slave valve
positioned within the chamber. The slave valve isolates the second
valve housing from the valve housing outlet when the slave valve is
positioned in a seated slave position. The slave valve places the
second valve housing in fluid communication with the valve housing
outlet when the slave valve is located in an open slave position.
The method further includes the steps of providing an internal
combustion engine having an engine air inlet, a first engine
exhaust outlet, and a second engine exhaust outlet. The first
engine exhaust outlet is in fluid communication with the first
valve housing inlet, the second engine exhaust outlet is in fluid
communication with the second valve housing inlet, and the engine
air inlet is in fluid communication with the valve housing outlet.
The method still further includes the step of moving the master
valve a first distance from the seated master position to an
intermediate master position while the slave valve is positioned in
the seated slave position. The method yet further includes the step
of moving the master valve a second distance from the intermediate
master position to the open master position so as to cause movement
of the slave valve from the seated slave position to the open slave
position whereby engine exhaust is enabled to flow from the first
and second engine exhaust outlet to the engine air inlet.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of an internal combustion engine 10
which incorporates the features of the present invention
therein;
FIG. 2 is a partial cross sectional view of the internal combustion
engine 10 taken along line 2--2 of FIG. 1, as viewed in the
direction of the arrows;
FIG. 3 is a perspective view of the internal combustion engine 10
of FIG. 1 with a portion of the engine head 20 and the engine block
18 cut away for clarity of description;
FIG. 4 is an enlarged cross sectional view of the housing 26 of the
EGR valve assembly 14 of the internal combustion engine 10 of FIG.
1;
FIG. 5 is an exploded cross sectional view of the master valve 60
and the slave valve 80 of the EGR valve assembly 14 of the internal
combustion engine 10 of FIG. 1;
FIG. 6 is an exploded perspective view of the master valve 60 and
the slave valve 80 of FIG. 5;
FIG. 7 is enlarged cross sectional view of the EGR valve assembly
14 with the master valve 60 and slave valve 80 shown in their
respective seated positions, note that the solenoid 50 is not shown
in cross section for clarity of description;
FIG. 8 is view similar to FIG. 7, but showing the master valve 60
as it begins to move out of the seated master position; and
FIG. 9 is view similar to FIG. 7, but showing both the master valve
60 and the slave valve 80 positioned in their respective open
positions.
BEST MODE FOR CARRYING OUT THE INVENTION
While the invention is susceptible to various modifications and
alternative forms, a specific embodiment thereof has been shown by
way of example in the drawings and will herein be described in
detail. It should be understood, however, that there is no intent
to limit the invention to the particular form disclosed, but on the
contrary, the intention is to cover all modifications, equivalents,
and alternatives falling within the spirit and scope of the
invention as defined by the appended claims.
Referring now to FIGS. 1-3, there is shown an internal combustion
engine 10 such as a six-cylinder turbocharged diesel engine. The
internal combustion engine 10 includes an EGR assembly 13, an
engine block 18, an engine head 20, and a valve cover 12.
As shown in FIG. 2, the engine block 18 has a cylinder 54 defined
therein. In a known manner, a piston 56 is operatively housed
within the cylinder 54. In particular, during an upward stroke, the
piston 56 translates in the general direction of arrow 57 of FIG.
2. During a downward stroke, the piston 56 translates in the
general direction of arrow 58 of FIG. 2.
The piston 56 is coupled to a first end of a connecting rod 66,
whereas a second end of the connecting rod 66 is connected to a
crankshaft 68. During the upward stroke of the piston 56, the
connecting rod 66 is likewise translated in the general direction
of arrow 57 of FIG. 2. During the downward stroke of the piston 56,
the connecting rod 66 is likewise translated in the general
direction of arrow 58 of FIG. 2. In both cases, the crankshaft 68
rotates in the direction of arrow 70 of FIG. 2.
The engine head 20 includes a number of head air inlet ports 37 and
head exhaust outlet ports 35. An engine air inlet or intake
manifold 17 places the head air inlet ports 37 in fluid
communication with an air intake line 43 associated with the
internal combustion engine 10. A pair of engine exhaust outlets or
exhaust manifolds 15, 16 places the head exhaust outlet ports 35 in
fluid communication with a turbocharger and a tailpipe (not shown)
associated with the internal combustion engine 10. It should be
appreciated that the exhaust manifold 15 is in fluid communication
with the head exhaust ports 35 of each of the front three cylinders
of the internal combustion engine 10, whereas the exhaust manifold
16 is in fluid communication with the head exhaust ports 35 of the
rear three cylinders.
An upper portion of the engine head 20 includes a valve and rocker
arm area 21. Within the valve and rocker arm area 21 is an exhaust
valve assembly 24, an intake valve assembly 94, an exhaust rocker
arm 22, and an intake rocker arm 92. It should be appreciated that
when the valve cover 12 is sealably secured to the engine head 20
an engine lubricant, such as oil, is contained therein so as to
lubricate a number of components associated with the internal
combustion engine 10.
When the exhaust valve assembly 24 is placed in a closed position,
as shown in FIG. 2, the cylinder 54 is isolated from the head
exhaust outlet ports 35 and hence the exhaust manifolds 15, 16.
When the exhaust valve assembly 24 is placed in an open position,
the cylinder 54 is in fluid communication with the exhaust
manifolds 15, 16 through the head exhaust outlet ports 35. The
exhaust valve assembly 24 includes an exhaust valve member 27 and
an exhaust spring 25 concentrically mounted about the exhaust valve
member 27. The exhaust spring 25 applies a force or bias to the
exhaust valve member 27 that biases the exhaust valve assembly 24
into the closed position, as shown in FIG. 2. Hence, the exhaust
valve assembly 24 is held in the closed position until urged by the
exhaust rocker arm 22 into the open position.
The exhaust rocker arm 22 is movably secured to the engine head 20.
In particular, the exhaust rocker arm 22 is free to pivot about a
rocker shaft 23 which is non-movably secured to the engine head 20.
A first end 78 of the exhaust rocker arm 22 is operatively coupled
to the exhaust valve member 27, whereas a second end 79 of the
exhaust rocker arm 22 is operatively coupled to a first end of an
exhaust pushrod 19 (see FIG. 2). A second end of the exhaust
pushrod 19 is operatively coupled to a camshaft 72.
The camshaft 72 includes a first cam lobe 73 which is moved into
and out of contact with the second end of the exhaust pushrod 19
during rotation of the camshaft 72. When the cam lobe 73 is rotated
into contact with the second end of the exhaust pushrod 19, the
exhaust pushrod 19 is urged in the general direction of arrow 57 of
FIG. 2. As the exhaust pushrod 19 is urged in the general direction
of arrow 57, the exhaust rocker arm 22 pivots about the rocker
shaft 23 thereby causing the first end 78 of the exhaust rocker arm
22 to be urged in the general direction of arrow 58 thereby
likewise urging the exhaust valve member 27 in the general
direction of arrow 58. When the force exerted on the exhaust valve
member 27 by the first end 78 of the exhaust rocker arm 22 is
greater in magnitude than the spring bias generated by the exhaust
spring 25, the exhaust valve member 27 is moved in the general
direction of arrow 58 thereby positioning the exhaust valve
assembly 24 in the open position. When the camshaft 72 is rotated
beyond the maximum height of the cam lobe 73, the spring bias of
the exhaust spring 25 urges the exhaust valve member 27 in the
general direction of arrow 57 thereby returning the valve assembly
24 to the closed position. It should be appreciated that as the
exhaust valve member 27 is urged in the general direction of arrow
57 by the exhaust spring 25, the first end 78 of the exhaust rocker
arm 22 is likewise urged in the general direction of arrow 57 which
causes the exhaust rocker arm 22 to pivot about the rocker shaft 23
thereby causing the second end 79 of the exhaust rocker arm 22 to
be urged in the general direction of arrow 58.
It should therefore be appreciated that as the exhaust valve
assembly 24 is placed in the open position, exhaust gases within
the cylinder 54 are allowed to advance from the cylinder 54,
through the head exhaust outlet ports 35, and into the exhaust
manifolds 15, 16. It should further be appreciated that as the
exhaust valve assembly 24 is placed in the closed position, the
cylinder 54 is isolated from the exhaust manifolds 15, 16 thereby
inhibiting advancement of the exhaust gases out of the cylinder
54.
Similarly, when the intake valve assembly 94 is placed in a closed
position, as shown in FIG. 3, the cylinder 54 is isolated from the
head air inlet ports 37 and hence the intake manifold 17. When the
intake valve assembly 94 is placed in an open position, the
cylinder 54 is in fluid communication with the intake manifold 17
through the head air inlet ports 37. As shown in FIG. 3, the intake
valve assembly 94 includes an intake valve member 97 and an intake
spring 95 concentrically mounted about the intake valve member 97.
The intake spring 95 applies a force or bias to the intake valve
member 97 that biases the intake valve assembly 94 into the closed
position. Hence, the intake valve assembly 94 is held in the closed
position until urged by the intake rocker arm 92 into the open
position.
The intake rocker arm 92 is movably secured to the engine head 20.
In particular, the intake rocker arm 92 is free to pivot about the
rocker shaft 23. A first end 88 of the intake rocker arm 92 is
operatively coupled to the intake valve member 97, whereas a second
end 89 of the intake rocker arm 92 is operatively coupled to a
first end of an intake pushrod (not shown) . The second end of the
intake pushrod is operatively coupled to the camshaft 72.
The camshaft 72 includes a second cam lobe (not shown) which is
moved into and out of contact with the second end of the intake
pushrod during rotation of the camshaft 72. When the cam lobe is
rotated into contact with the intake pushrod, the intake pushrod is
urged in the general direction of arrow 57 of FIG. 3. As the intake
pushrod is urged in the general direction of arrow 57, the intake
rocker arm 92 pivots about the rocker shaft 23 thereby causing the
first end 88 of the intake rocker arm 92 to be urged in the general
direction of arrow 58 of FIG. 3 thereby likewise urging the intake
valve member 97 in the general direction of the arrow 58. When the
force exerted on the intake valve member 97 by the first end 88 of
the intake rocker arm 92 is greater in magnitude than the spring
bias generated by the intake spring 95, the intake valve member 97
is moved in the general direction of arrow 58 thereby positioning
the intake valve assembly 94 in the open position. When the
camshaft 72 is rotated beyond the maximum height of the cam lobe
that is acting upon the intake pushrod, the spring bias of the
intake spring 95 urges the intake valve member 97 in the general
direction of arrow 57 thereby returning the intake valve assembly
94 to the closed position. It should be appreciated that as the
intake valve member 97 is urged in the general direction of arrow
57 by the intake spring 95, the first end 88 of the intake rocker
arm 92 is likewise urged in the general direction of arrow 57 which
causes the intake rocker arm 92 to pivot about the rocker shaft 23
thereby causing the second end 89 of the intake rocker arm 92 to be
urged in the general direction of arrow 58.
It should therefore be appreciated that as the intake valve
assembly 94 is placed in the open position, air (along with any
exhaust gases which have been routed to the intake manifold 17 by
the EGR assembly 13) within the intake manifold 17 is advanced
through the head air inlet ports 37, and into the cylinder 54. It
should be further appreciated that as the intake valve assembly 94
is placed in the closed position, the cylinder 54 is isolated from
intake manifold 17 thereby inhibiting advancement of air from the
intake manifold 17 into the cylinder 54.
The internal combustion engine 10 is a four stroke engine. The
first stroke is an intake stroke, during which the exhaust valve
assembly 24 is positioned in the closed position and the intake
valve assembly 94 is positioned in the open position. Furthermore,
during the intake stroke, the piston 56 is advanced in the general
direction of arrow 58 thereby creating a partial vacuum in the
cylinder 54. This partial vacuum causes air to be advanced from the
intake manifold 17, through the head air inlet ports 37, and into
the cylinder 54. Advancing to a compression stroke, the intake
valve assembly 94 and the exhaust valve assembly 24 are both
positioned in their respective closed positions. As the piston 56
moves upward in the general direction of arrow 57, it compresses
the air in the cylinder 54. As the piston 56 continues to advance
toward a top of its stroke, a fuel, such as diesel fuel, is
introduced into the cylinder 54 thereby creating a fuel and air
mixture with the air present in the cylinder 54. Near the top of
the stroke of the piston 56, the fuel and air mixture is ignited by
the heat generated as a result of compressing the fuel and air
mixture. Ignition of the fuel and air mixture advances the internal
combustion engine 10 to a power stroke in which the intake valve
assembly 94 and the exhaust valve assembly 24 are both positioned
in their respective closed positions. The fuel and air mixture is
combusted and exhaust gases are formed. The formation of the
exhaust gases generates pressure. This pressure acts upon the
piston 56 to create a force which drives the piston 56 in the
general direction of arrow 58. Thereafter, the internal combustion
engine 10 is advanced to an exhaust stroke during which the exhaust
valve assembly 24 is positioned in the open position and the intake
valve assembly 94 is positioned in the closed position. Since the
pressure generated by the exhaust gases in the cylinder 54 is
greater than the pressure in the exhaust manifolds 15, 16, the
exhaust gases advance from the cylinder 54, through the head
exhaust outlet ports 35, and into the exhaust manifolds 15, 16.
During certain operating conditions of the internal combustion
engine 10, it is desirable to inhibit the formation of NO.sub.x by
introducing chemically inert exhaust gases into the cylinder 54
during the intake stroke. Hence, the EGR assembly 13 routes exhaust
gases from the exhaust manifolds 15, 16 to the intake manifold 17.
In particular, the EGR assembly 13 includes an EGR valve assembly
14 which selectively places the exhaust manifolds 15, 16 in fluid
communication with the intake manifold 17 during such operating
conditions.
Referring now to FIG. 4, the EGR valve assembly 14 includes a
housing 26 having a chamber 27 defined therein. It should be
appreciated that the housing 26 may be embodied as a number of
separate components as shown in order to facilitate the manufacture
and assembly of the EGR valve assembly 14. Alternately, the housing
26 may be embodied as a single, integral component. The housing 26
further defines a first valve housing inlet 28, a second valve
housing inlet 30, a valve housing outlet 32, and a plunger opening
34. The first inlet 28, the second inlet 30, the outlet 32, and the
plunger opening 34 are each in fluid communication with the chamber
27.
As shown in FIG. 3 the exhaust manifold 15 is in fluid
communication with the first inlet 28 of the EGR valve assembly 14,
whereas the exhaust manifold 16 is in fluid communication with the
second inlet 30. In particular, the exhaust manifold 15 is coupled
to the first inlet 28 via a line 74, whereas the exhaust manifold
16 is coupled to the second inlet 30 via a line 75 (see FIG. 3).
The outlet 32 is in fluid communication with the intake manifold
17. More specifically, the outlet 32 is coupled to the intake
manifold 17 via a line 76 (see FIG. 2).
The housing 26 further has a master valve opening 39 defined
therein which places the first inlet 28 in fluid communication with
the outlet 32. As shown in FIG. 4, a portion of the master valve
opening 39 defines a master valve seat 40. The housing 26 also has
a slave valve opening 41 defined therein which places the second
inlet 30 in fluid communication with the outlet 32. A portion of
the slave valve opening defines a slave valve seat 42.
As shown in FIG. 7, the EGR valve assembly 14 further includes a
master valve 60 positioned in the chamber 27 so as to be received
through both the master valve opening 39 and the slave valve
opening 41. The master valve 60 is free to translate in the general
directions of arrows 99 and 100 of FIG. 7. The master valve 60
includes a master seating surface 61 (see FIGS. 5 and 6). When the
master valve 60 is positioned in a seated master position as shown
in FIG. 7, the master seating surface 61 sealably contacts the
master valve seat 40 so as to prevent advancement of exhaust gases
therebetween. It should therefore be appreciated that when
positioned in the seated master position, the master valve 60
isolates the first inlet 28 from the outlet 32. It should also be
appreciated that as the master valve 60 is moved out of the seated
master position in the general direction of the arrow 99 so as to
position the master valve 60 in an open master position (see FIG.
9), the first inlet 28 is placed in fluid communication with the
outlet 32. In particular, when the master valve 60 is positioned in
the open master position, exhaust gases are advanced from the first
inlet 28 to the outlet 32 through the master valve opening 39. Such
a configuration thus allows exhaust gases to be advanced from the
exhaust manifold 15 to the intake manifold 17 via a fluid path that
includes the line 74, the first inlet 28, the master valve opening
39, the outlet 32, and the line 76.
As shown in FIGS. 7-9, the EGR valve assembly 14 further includes a
plunger 44 and a spring 46. One end of the plunger 44 is received
through the plunger opening 34 and is free to move in the general
directions of arrows 99 and 100. A second end of the plunger 44 is
operatively coupled to an actuator, such as a solenoid 50. The
solenoid 50 is provided to selectively pull or otherwise move the
plunger 44 in the general direction of arrow 99.
The plunger 44 further includes a plunger body 47 and a disk 48
which extends radially outward from the plunger body 47. The spring
46 is positioned concentrically about the plunger body 47, and is
interposed between a contact surface 51 of the housing 26 and the
disk 48. Hence, the spring 46 applies a force or bias to the
plunger 44 thereby urging the plunger 44 in the general direction
of arrow 100. As shown in FIG. 7, the disk 48 of plunger 44
contacts the master valve 60. Hence, the spring bias generated by
the spring 46 urges the master valve 60 in the general direction of
arrow 100. It should be appreciated that the spring bias of the
spring 46 positions the master valve 60 in the seated master
position. It should further be appreciated that when the solenoid
50 moves the plunger 44 in the general direction of arrow 99, the
spring bias of the spring 46 is no longer exerted on the master
valve 60, thus allowing the master valve 60 to be moved from the
seated master position without having to overcome the spring bias
of the spring 46.
The EGR valve assembly 14 further includes a slave valve 80 and a
second spring 82. As shown in FIGS. 5 and 6, the slave valve 80 has
a cylindrical passageway 83 defined therethrough. The slave valve
80 is concentrically mounted about the master valve 60. In
particular, the master valve 60 is received through the cylindrical
passageway 83. The second spring 82 is mounted concentrically about
the master valve 60, and is interposed between the disk 48 of the
plunger 44 and a surface 85 of the slave valve 80. The second
spring 82 applies a force or bias to the surface 85 of the slave
valve 80 so as to urge the slave valve 80 in the general direction
of arrow 100 of FIGS. 7-9. It should therefore be appreciated that
the spring bias of the second spring 82 urges the slave valve 80 in
the general direction of arrow 100 so as to position the slave
valve 80 in a seated slave position, as shown in FIGS. 7 and 8. It
should further be appreciated that when the solenoid 50 moves the
plunger 44 in the general direction of arrow 99, the bias of the
second spring 82 is no longer exerted on the slave valve 80, thus
allowing the slave valve 80 to be moved without having to overcome
the spring bias of the second spring 82.
As with the master valve 60, the slave valve 80 is free to
translate in the general directions of arrows 99 and 100. Moreover,
the slave valve 80 includes a slave seating surface 81 (see FIGS. 5
and 6). When the slave valve 80 is positioned in a seated slave
position, as shown in FIGS. 7 and 8, the slave seating surface 81
sealably contacts the slave valve seat 42 (see FIG. 4) so as to
prevent advancement of exhaust gases therebetween. It should
therefore be appreciated that when the slave valve 80 is positioned
in the seated slave position, the slave valve 80 isolates the
second inlet 30 from the outlet 32. It should also be appreciated
that as the slave valve 80 is moved out of the seated slave
position in the general direction of arrow 99 so as to position the
slave valve 80 in an open slave position (see FIG. 9), the second
inlet 30 is placed in fluid communication with the outlet 32 (see
FIG.9). In particular, when the slave valve 80 is positioned in the
open slave position, exhaust gases are advanced from the second
inlet 30 to the outlet 32 through the slave valve opening 41. Such
a configuration thus allows exhaust gases to be advanced from the
exhaust manifold 16 to the intake manifold 17 via a fluid path
which includes the line 75, the second inlet 30, the slave valve
opening 41, the outlet 32, and the line 76.
The master valve 60 further has a shoulder 62 defined thereon (see
FIGS. 5 and 6). As the master valve 60 moves in the general
direction of arrow 99, the shoulder 62 is urged into contact with a
surface 84 of the slave valve 80. In particular, the master valve
60 must first move in the general direction of arrow 99 a short
distance D (see in FIG. 7) before the shoulder 62 of the master
valve 60 contacts the surface 84 of the slave valve 80. Such a
configuration allows the slave valve 80 to seat and unseat
independently of the seating and unseating of the master valve 60.
In particular, such configuration allows the slave seating surface
81 of the slave valve 80 to move independently of the of the master
seating surface 61 of master valve 60. Such independent seating and
unseating of the master valve 60 and the slave valve 80 is
particularly useful to reduce the effects of a large temperature
gradient which is present across the housing 26. More specifically,
a large temperature gradient arises across the housing 26 when hot
engine exhaust gases are introduced into the first inlet 28 and the
second inlet 30 while cooler intake air is present in the outlet
32. Such a large temperature gradient may distort or otherwise
alter the size and/or shape of the master valve opening 39
(including the master valve seat 40) and the slave valve opening 41
(including the slave valve seat 42) such that the relative
orientation therebetween is altered. Independent seating and
unseating of the master valve 60 and the slave valve 80 allows the
EGR valve assembly 14 to accommodate for such distortions. Hence,
the magnitude of the distance D is predetermined to be large enough
to allow the master valve 60 to seat and unseat independently of
the slave valve 80 in order to accommodate for distortion of the
housing 26, yet small enough to allow the master valve 60 and the
slave valve 80 to open at essentially the same time. Preferably,
the distance D has a magnitude of approximately 1.0 millimeter.
As shown in FIGS. 7-9, the master valve 60 and the slave valve 80
divide the chamber 27 into a chamber portion 102 and a chamber
portion 104. The master valve 60 further has a pressure
compensation channel 63 defined therein. The channel 63 places the
chamber portion 102, the chamber portion 104, and the outlet 32 in
fluid communication with each other. Therefore, the chamber portion
102, chamber portion 104, and outlet 32 are each maintained at the
same relative pressure. As mentioned above, the outlet 32 is in
fluid communication with the intake manifold 17. Therefore, the
chamber portion 102, the chamber portion 104, and the outlet 32 are
each maintained at the same relative pressure as the intake
manifold 17.
The master valve 60 has a pair of end surfaces 110 and 116, as
shown in FIGS. 5 and 6. Moreover, the master valve 60 has a pair of
intermediate surfaces 112 and 114. When the master valve 60 is
positioned in the chamber 27, fluid pressure in the chamber portion
102 acts upon the surface 116, whereas fluid pressure in the
chamber portion 104 acts upon the surface 110. Moreover, fluid
pressure in the outlet 32 acts upon both the surface 112 and the
surface 114. Fluid pressure acting on the surface 110 and the
surface 114 urges the master valve 60 in the general direction of
arrow 100, whereas fluid pressure acting on the surface 112 and the
surface 116 urges the master valve 60 in the general direction of
arrow 99. The master valve 60 is preferably configured such that
the sum of the surface areas of the surfaces 116 and 112 is
slightly greater in magnitude than the sum of the surface areas of
the surfaces 110 and 114. Since the magnitude of fluid pressure in
the chamber portions 102 and 104 is approximately equal to the
magnitude of fluid pressure in the outlet 32, the net force exerted
on the master valve 60 by fluid pressure on the surfaces 110, 112,
114, and 116 creates a slight bias in the general direction of
arrow 99. It should be appreciated that during operation of the
internal combustion engine 10, the net force exerted on the master
valve 60 by fluid pressure acting on the surfaces 110, 112, 114,
and 116 will remain biased in the general direction of arrow 99
despite changes in the magnitude of fluid pressure in the intake
manifold 17 and hence the outlet 32.
When the slave valve 80 is positioned in the chamber 27, fluid
pressure in the chamber portion 102 acts upon the surface 85,
whereas fluid pressure in the outlet 32 acts upon the surface 84.
In particular, fluid pressure in the outlet 32 acting on the
surface 84 urges the slave valve 80 in the general direction of
arrow 99, whereas fluid pressure in chamber portion 104 acting on
the surface 85 urges the slave valve 80 in the general direction of
arrow 100. The slave valve 80 is preferably configured such that
the surface area of the surface 84 is slightly greater in magnitude
than the surface area of the surface 85. Since the magnitude of
fluid pressure in the chamber portion 104 is approximately equal to
the magnitude of fluid pressure in the outlet 32, the net force
exerted on the slave valve 80 by fluid pressure exerted on the
surfaces 84 and 85 creates a slight bias in the general direction
of arrow 99. It should be appreciated that during operation of the
internal combustion engine 10, the net force exerted on the slave
valve 80 by fluid pressure acting on the surfaces 84 and 85 will
remain biased in the general direction of arrow 99 despite changes
in the magnitude of fluid pressure in the intake manifold 17 and
hence the outlet 32.
The slave valve 80 further has a pair of intermediate surfaces 86
and 87 (see FIGS. 5 and 6). Fluid pressure in the second inlet 30
acts upon both the surfaces 86 and 87. In particular, fluid
pressure in the second inlet 30 acting on the surface 86 urges the
slave valve in the general direction of arrow 99, whereas fluid
pressure in the second inlet 30 acting on the surface 87 urges the
slave valve 80 in the general direction of arrow 100. The slave
valve 80 is preferably configured such that the surface area of the
surface 86 is slightly greater in magnitude than the surface area
of the surface 87. Thus, the net force exerted by fluid pressure
acting on the surfaces 86 and 87 creates a slight bias in the
general direction of arrow 99. It should be appreciated that during
operation of the internal combustion engine 10, the primary force
exerted on the slave valve 80 by fluid pressure on the surfaces 86
and 87 will remain biased in the general direction of arrow 99
despite changes in the magnitude of fluid pressure in the second
inlet 30. Therefore, it should be appreciated that the primary
force urging the slave valve 80 in the general direction of arrow
100 is the spring bias generated by the second spring 82. Whereas,
the primary force urging the slave valve 80 in the general
direction of arrow 99 is the sum of the bias created by pressure
exerted by fluid in the outlet 32 on the surfaces 84 and 85 and the
bias created by pressure exerted on the surfaces 86 and 87 by fluid
in the second inlet 30.
Similarly, the master valve 60 further has a pair of intermediate
surfaces 120 and 122 (see FIGS. 5 and 6). Fluid pressure within the
first inlet 28 acts upon both of the surfaces 120 and 122. In
particular, fluid pressure in the first inlet 28 acting on the
surface 120 urges the master valve 60 in the general direction of
arrow 99, whereas fluid pressure in the first inlet 28 acting on
surface 122 urges the master valve 60 in the general direction of
arrow 100. The master valve 60 is preferably configured such that
the surface area of the surface 120 is slightly greater in
magnitude than the surface area of the surface 122. Thus, the net
force on the master valve 60 as a result of fluid pressure acting
on the surfaces 120 and 122 creates a slight bias in the general
direction of arrow 99. Therefore, it should be appreciated that the
primary force urging the master valve 60 in the general direction
of arrow 100 is the spring bias generated by the first spring 46,
whereas the primary force urging the master valve 60 in the general
direction of arrow 99 is the sum of the bias exerted by fluid
pressure in the first inlet 28 acting on the surfaces 120 and 122
and the bias exerted by fluid pressure in the outlet 32 acting on
the surfaces 110, 112, 114, and 116.
Such a configuration allows for rapid opening and closing of the
EGR valve assembly 14. In particular, once the spring biases of the
spring 46 and spring 82 have been removed or otherwise reduced by
the solenoid 50, the master valve 60 and the slave valve 80 may be
quickly moved in the general direction of arrow 99 thereby
providing for rapid opening of the EGR valve assembly 14. The
master valve 60 and the slave valve 80 may then be quickly moved in
the general direction of arrow 100 by actuation of the solenoid 50
thereby providing for rapid closing of the EGR valve assembly
14.
It should also be appreciated that the magnitude of the spring bias
of the spring 46 is predetermined such that the sum of the bias
exerted by fluid pressure in the first inlet 28 acting on the
surfaces 120 and 122 and the bias exerted by fluid pressure in the
outlet 32 acting on the surfaces 110, 112, 114, and 116 is less
than the spring bias of the spring 46 under even the most extreme
conditions (e.g. the maximum pressure in the exhaust manifold 15).
It should further be appreciated that the magnitude of the spring
bias of the spring 82 is predetermined such that the bias created
by pressure exerted by fluid in the outlet 32 on the surfaces 84
and 85 and the bias created by pressure exerted on the surfaces 86
and 87 by fluid in the second inlet 30 is less than the spring bias
of the spring 82 under even the most extreme conditions (e.g. the
maximum pressure in the exhaust manifold 16). Therefore, the master
valve 60 is maintained in the seated master position by the bias of
spring 46 and the slave valve 80 is maintained in the seated slave
by the bias of spring 82 under such extreme conditions thereby
providing fail safe operation.
Industrial Applicability
In operation, the EGR valve assembly 14 remains in a fail safe mode
of operation until the solenoid 50 is actuated. During such fail
safe operation, advancement of exhaust gases from the exhaust
manifolds 15, 16 to the intake manifold 17 is inhibited. In
particular, the first spring 46 biases the master valve 60 into the
seated master position which isolates the first inlet 28 from the
outlet 32. Moreover, the second spring 82 biases the slave valve 80
into the seated slave position which isolates the second inlet 30
from the outlet 32.
However, it is desirable to inhibit the formation of NO.sub.x under
certain engine operating conditions. Hence, during such operating
conditions, an engine control module (not shown) associated with
the internal combustion engine 10 generates a control signal which
is sent to the solenoid 50 thereby causing the plunger 44 to
retract in the general direction of arrow 99 of FIGS. 7-9.
Actuation of the solenoid 50 compresses the spring 46 thereby
removing the spring bias being exerted on the master valve 60. As
described above, without the spring bias of the spring 46, the
master valve 60 will be urged in the general direction of arrow 99
by fluid pressure in the first inlet 28 and the outlet 32. The
master valve 60 moves a short distance D to position the master
valve in an intermediate master position shown in FIG. 8. In the
intermediate master position, the shoulder 62 of the master valve
60 contacts the surface 84 of the slave valve 80. As the master
valve 60 moves toward the surface 84 of the slave valve 80, the
master valve 60 moves out of the seated master position thereby
allowing exhaust gases to be advanced from the first inlet 28,
through the master valve opening 39, and into the outlet 32 in the
general direction of arrows 130 of FIG. 8.
As the plunger moves in the general direction of arrow 99, the
spring bias associated with the second spring 82 is reduced thereby
allowing the master valve 60 to urge the slave valve 80 in the
general direction of arrow 99. In particular, the force exerted on
the surface 84 of the slave valve 80 by the shoulder 62 of the
master valve 60 is greater in magnitude than the reduced spring
bias of the second spring 82 acting on the surface 85 of the slave
valve 80. Hence, both the master valve 60 and the slave valve 80
move together in the general direction of arrow 99. As shown in
FIG. 9, when the master valve 60 and the slave valve 80 move in the
general direction of arrow 99, exhaust gases flow from the first
inlet 28 in the general direction of arrows 130 into the outlet 32.
Exhaust gases also flow from the second inlet 30 in the general
direction of arrows 132 into the outlet 32. Due to the coupled
movement of the slave valve 80 and the master valve 60, the flow
rate of the exhaust gases flowing from the second inlet 30 to the
outlet 32 is substantially equivalent to the flow rate of the
exhaust gases flowing from the first inlet 28 to the outlet 32.
Hence, a first amount of exhaust gas is advanced from the exhaust
manifold 15, through the line 74, the first inlet 28, the master
valve opening 39, the outlet 32, the line 76, and into the intake
manifold 17. A second amount of exhaust gas is also advanced from
the exhaust manifold 16, through the line 75, the second inlet 30,
the slave valve opening 41, the outlet 32, the line 76, and into
the intake manifold 17. It should be appreciated that the first
amount of exhaust gases is substantially equal to the second amount
of exhaust gases.
At a predetermined time, the engine control module ceases to send
the control signal thereby deactuating the solenoid 50. Such
deactuation allows the spring 46 to return the plunger 44 to its
original position (see FIG. 7). In particular, the spring bias of
the spring 46 returns the master valve 60 to the seated master
position thus isolating the first inlet 28 from the outlet 32.
Similarly, the spring bias of the spring 46 provides the primary
force that returns the slave valve 80 to the seated slave position,
whereas the second spring 82 provides a secondary force that allows
the slave valve 80 to seat independently of the master valve 60
thus isolating the second inlet 30 from the outlet 32. It should be
appreciated that both the master valve 60 and the slave valve 80
will remain in their respective seated positions until a subsequent
control signal is sent by the engine control module.
While the invention has been illustrated and described in detail in
the drawings and foregoing description, such illustration and
description is to be considered as exemplary and not restrictive in
character, it being understood that only the preferred embodiment
has been shown and described and that all changes and modifications
that come within the spirit of the invention are desired to be
protected.
For example, although the internal combustion engine 10 is herein
described as being configured with two separate exhaust manifolds
15, 16, and has significant advantages thereby in the present
invention, a single or unified exhaust manifold could replace the
manifolds 15, 16. In such a configuration, a single or unified line
would replace the lines 74 and 75. The unified line would couple
the unified exhaust manifold to both the first inlet 28, and the
second inlet 30 of the housing 26 thereby allowing the valve
assembly 14 to be used in an internal combustion engine 10
configured with a unified exhaust manifold.
* * * * *